Amine oxides are materials which are used in a variety of applications, e.g., in the treatment of fabrics and in the preparation of hair conditioners and shampoos, toothpaste, laundry detergent powders, fabric softeners, toilet soap bars, and cosmetics, as well as in other applications. They are most commonly prepared by reacting the appropriate tert-amine, generally a non-aromatic amine such as a trialkylamine, with hydrogen peroxide.
It appears that earlier amine oxide syntheses from non-aromatic amines and hydrogen peroxide were normally conducted in the absence of catalyst or other substances that could increase the reaction rate to an acceptable degree. However, it later became preferred to conduct these syntheses in a carbon dioxide atmosphere to obtain what U.S. Pat. No. 4,247,480 (Murata et al.) describes as a "catalytic effect"--a reaction rate increase which European Patent Application 0 320 694 (Bauer et al.) indicates to be more probably provided by a carbon dioxide reaction product than by carbon dioxide itself, since carbon dioxide is reactive with both water and tert-amines.
When synthesized in the conventional manner so as to be provided as dilute solutions (as in Murata et al. and Bauer et al.), the amine oxide products have the same acceptable color whether they are prepared in the presence or absence of carbon dioxide. This is not the case, however, when the amine oxides are prepared by the newer high solids processes, such as the processes of U.S. Pat. Nos. 4,970,340 (Smith) and 5,130,488 (Smith et al.). In these high solids processes, i.e., processes wherein tert-amines are reacted with hydrogen peroxide in a liquid medium which constitutes not more than 50% by weight of the reaction mixture, the amine oxides have acceptable color when they are prepared in the absence of carbon dioxide; but they are intensely colored when a carbon dioxide atmosphere is used to speed the reaction.